Purpose: Oncology clinical practice guidelines recommend bone-modifying agents (BMAs) to decrease skeletal-related events for patients with metastatic castration-resistant prostate cancer (mCRPC) and against BMAs to decrease skeletal-related events in metastatic castration-sensitive prostate cancer (mCSPC). Previous studies have identified gaps in guideline-concordant BMA use, but interprovider variation is poorly understood.
Methods: We conducted a multicenter, retrospective, cohort study of patients diagnosed with prostate cancer and bone metastases during 2020-2021. The sample included three health systems in the Northeastern United States: two community-based networks and one academic cancer center. Patient characteristics and BMA use (zoledronic acid and denosumab) were ascertained via chart review. The outcomes of interest were BMA overuse during castration-sensitive prostate cancer (CSPC; defined as BMA initiation before emergence of castration-resistant prostate cancer [CRPC], among patients without a comorbid condition for which BMA therapy may be appropriate: osteoporosis, osteopenia, or osteoporotic fracture) and appropriate use during CRPC (BMA initiation after emergence of CRPC).
Results: There were 153 eligible patients, 51 from each health system. At diagnosis, 14 (9%) patients had documented osteoporosis or osteopenia, 22 (14%) had previous osteoporotic fracture, and 36 (24%) had chronic renal insufficiency. Among 95 patients assessable for overuse during CSPC, 16% (n = 17) received BMA (ranging from 13% to 21% among the three systems). Among 55 patients who developed CRPC, 44% (n = 24) had initiated BMA therapy as of most recent follow-up. There was greater variation in use during CRPC, ranging from 22% to 54% across the three systems.
Conclusion: BMA overuse in mCSPC was rare, potentially reflecting de-implementation following evidence of lack of benefit. Appropriate BMA use for patients with mCRPC varies substantially among clinicians and health care systems. Interventions to increase guideline-concordant care may improve outcomes.